Wild Buckwheat (Polygonum convolvulus (=Fallopia convolvulus)) is a dicot weed in the Polygonaceae family. In Alberta this weed first evolved resistance to Group B/2 herbicides in 2007 and infests Peas, and Wheat. Group B/2 herbicides are known as ALS inhibitors (Inhibition of acetolactate synthase ALS (acetohydroxyacid synthase AHAS)). Research has shown that these particular biotypes are resistant to florasulam, thifensulfuron-methyl, and tribenuron-methyl and they may be cross-resistant to other Group B/2 herbicides.

The 'Group' letters/numbers that you see throughout this web site refer to the classification of herbicides by their site of action. To see a full list of herbicides and HRAC herbicide classifications click here.

Greenhouse trials comparing a known susceptible Wild Buckwheat biotype with this Wild Buckwheat biotype have been used to confirm resistance. For further information on the tests conducted please contact the local weed scientists that provided this information.

Genetics

Genetic studies on Group B/2 resistant Wild Buckwheat have not been reported to the site. There may be a note below or an article discussing the genetics of this biotype in the Fact Sheets and Other Literature

Mechanism of Resistance

The mechanism of resistance for this biotype is either unknown or has not been entered in the database. If you know anything about the mechanism of resistance for this biotype then please update the database.

Relative Fitness

There is no record of differences in fitness or competitiveness of these resistant biotypes when compared to that of normal susceptible biotypes. If you have any information pertaining to the fitness of Group B/2 resistant Wild Buckwheat from Alberta please update the database.

The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Alberta have been instrumental in providing you this information. Particular thanks is given to Hugh Beckie for providing detailed information.

Wild buckwheat is the most abundant broadleaf weed across the Prairie region of western Canada. Acetolactate synthase (ALS)-inhibiting herbicides are commonly used to control this species and other broadleaf weeds in cereal crops. A field survey in Alberta in 2007 identified a single population that was putatively resistant to ALS-inhibiting herbicides. In herbicide resistance screening in the greenhouse, all F1 progeny tested were resistant to the ALS-inhibiting herbicides thifensulfuron/tribenuron, a sulfonylurea herbicide, or florasulam, a triazolopyrimidine herbicide; dose response of shoot biomass indicated the population was 10- and 20-fold less sensitive to thifensulfuron/tribenuron and florasulam, respectively, than a susceptible control population. ALS gene sequencing of 24 F1 progeny indicated that the Trp574Leu target-site mutation was responsible for conferring ALS-inhibitor resistance in this biotype, the first global report of ALS-inhibitor resistance for this species. Because this mutation typically endows high-level resistance across all five ALS-inhibitor classes, this wild buckwheat biotype may only be controlled by a different site-of-action herbicide..

During 2008 and 2009, a study was conducted in 200 locations in Germany and Austria to monitor the frequency of occurence of various weeds and weed species and to evaluate the efficiency of herbicide treatments. The 10 most common weeds observed include goosefoot (Syngonium podophyllum), chickweed, black bindweed (Polygonum convolvulus), barnyard grass (Echinochloa crus-galli), chamomile types, field pansy (Viola arvensis) and dead nettle (Lamium spp.). The sole use of terbuthylazine proved to be effective for the control of some weed species e.g. Matricaria spp., Polygonum spp., and Chenopodium spp. The genetic resistance of some weed species e.g. Chenopodium album, Chenopodium ficifolium, Matricaria chamomilla [Chamomilla recutita], Polygonum aviculare, Polygonum convolvulus, Solanum nigrum to herbicides were also studied..

The aim of conducted research was the identification of resistance and cross-resistance of Polygonum aviculare, P. convolvulus and P. persicaria to photosystem II inhibiting herbicides (atrazine, simazine, metribuzine, metamitron, linuron, lenacil, bentazone and chloridazone). The research was conducted as monitoring tests. During eight years (2000-2007) seeds of weeds were collected from 243 fields in South-Western Poland. Resistance of biotypes was diagnosed by biological tests (evaluation of phytotoxicity, measurement of fresh plant mass and calculating of resistance index) and fluorescence method. Identified biotypes showed, in most cases, high level of resistance (IR>6). Most of Polygonum biotypes were resistant to herbicides from triazine group (artazine, simazine, metribuzine and metamitron), lenacil and chloridazone. Resistant biotypes of Polygonum were identified on 15-20% of monitored fields. Participation of resistant biotypes, for all monitored fields, in Polygonum communities did not exceed 40%. On monitored fields also several cases of cross-resistance was determined. Polygonum biotypes were resistant to atrazine and other triazines (simazine, metribuzine and metamitron), atrazine-lenacil and lenacil-chloridazone..

The efficacy of the biological test method and fluorescence method for the identification of weed biotypes showing resistance to herbicides (inhibitors of photosystem II) was evaluated. The materials used were seeds of Amaranthus retroflexus, Chenopodium album, Polygonum convolvulus, Sinapis arvensis, Solanum nigrum and Papaver rhoeas collected from crop fields in Lower Silesia, Poland. Susceptible and resistant biotypes of weeds were also analysed as controls. The degree of concurrence between both methods reached 78-100% for herbicides applied at post-emergence (linuron, bentazone, chlorotoluron and isoproturon), and 42-76% for herbicides applied at pre-emergence..

Imidazolinonies (IMIs) are a group of herbicides inhibiting acetolactate synthase (ALS) activity. They control the growth of many broadleaved weeds and annual grass species. Herbicide resistance against imidazolinonies has been transferred in some crop species, for example in oilseed rape. IMI-resistant oilseed rape cultivars have been developed by a mutation in ALS. They have been on the market for a few years, especially in North America. To determine if imazamox, an imidazolinone herbicide, and IMI-resistant oilseed rape cultivars are suitable for cultivation in Finland, 4 herbicide trials in 3 locations in Finland was conducted. Imazamox had no negative effect on yield or oil quality characters of IMI-resistant oilseed rape. Some transient chlorosis was observed immediately after the treatment, but it was not apparent after a few days. The effects of imazamox against the most troublesome weeds in oilseed field in Finland, Chenopodium album and Galium spurium, were very good. Imazamox had good or moderate effects on Stellaria media, whereas its effects on Viola arvensis, Lapsana communis and Fallopia convolvulus [Polygonum convolvulus] were insufficient. If the total weed number was high or the emergence of oilseed rape was slow, the application of imazamox increased the yield of oilseed rape compared to untreated control. Imazamox is a good alternative in controlling weeds for Finnish oilseed fields. Therefore, it would be beneficial to transfer the IMI-resistance into Finnish oilseed and turnip rape lines..

Glyphosate-resistant (GR) crops are produced over large areas in North America. A study was conducted at six western Canada research sites, i.e. in Beaverlodge, Lacombe and Lethbridge in Alberta, Brandon in Manitoba, and in Scott and Swift Current in Saskatchewan, to determine seed date, i.e. mid-April to early May (early) and mid-May to early June (late), and tillage system (conventional or low soil-disturbance direct-seeding) effects on weed populations in GR spring wheat and canola [rape] cropping systems from 2000 to 2003. Four-year wheat-canola-wheat-pea rotations were devised with varying levels of GR crops in the rotation. Weed populations were determined at pre- and post-in-crop herbicide application intervals in 2000 and 2003. Early seeding led to higher and more variable in-crop wild oat (Avena fatua) and wild buckwheat (Polygonum convolvulus [F. convolvulus]) populations. High frequencies of in-crop glyphosate wheat in the rotation usually improved weed management and reduced weed density and variability. Canonical discriminant analysis (CDA) across all locations revealed that by 2003, green foxtail (Setaria viridis), redroot pigweed (Amaranthus retroflexus), sowthistle spp. (Sonchus oleraceus, S. arvensis and S. asper), wild buckwheat and wild oat, all associated with the rotation lacking in-crop glyphosate. Similar CDA analyses for individual locations indicated specific weeds were associated with 3 years of in-crop glyphosate (Canada thistle (Cirsium arvense) at Brandon, henbit (Lamium amplexicaule) at Lacombe, and volunteer wheat, volunteer canola, and round-leaved mallow (Malva pusilla) at Lethbridge). However, only henbit at Lacombe and volunteer wheat at Lethbridge occurred at significant densities. Although excellent weed control was attained in rotations containing a high frequency of GR crops, the merits of more integrated approaches to weed management and crop production should also be considered. Overall, rotations including GR spring wheat did not significantly increase short-term weed management risks in conventional tillage or low soil-disturbance direct-seeding systems..